During an image capturing, a large amount of noise may exist in the image due to an imaging apparatus itself and an influence of surroundings. A visual effect of the image may be affected due to the large amount of noise. During an image processing, it requires de-noising the image so as to remove interference caused by the noise from the image. In a conventional image processing, a mean filter, an adaptive Wiener filter and a median filter may be adopted to de-noising of the image. The filters vary with types of the noise.